Water Tank Replacement - Stainless or Fiberglass

[svHyLyte]

Originally Posted by wgh52

I'm in the process of replacing my 30 year old stainless steel water tanks which have developed a leak. My initial thought was to replace with new stainless tanks, however, someone in the boat yard mentioned that their boat had fiberglass tanks. I'm wondering the pros and con's of fiberglass versus stainless steel. The tanks are under the teak and holly sole so this is not something I would like to do this again anytime soon.

I thought the experience of this group might help me with this decision.

Another alternative to replacing the tank is to use it as a container for a bladder tank. When we lost the tank in our old boat, I cut an opening in the top of the tank to gain access (later covered with a plastic inspection port), cleaned and dried the tank out and lined it with 1/8" neoprene as padding, and installed a bladder tank. The fix worked very well for 15 years, and as far as I know, is still working for the subsequent owners.

FWIW...

[Cheechako]

I would never go with fiberglass. yuck. You dont mention how hard it is to remove the tanks....? Often, the bad part is only on the bottom, you could have a new bottom welded on them and go another 30 years!

[wgh52]

I appreciate the comments and conversation concerning my project. There are currently two tanks with a capacity of 70 gallons each (total of 140 Gallons). The current tanks are baffled so lining would require removal of the baffles (at least two per tank; that is all I can see from the inspection port). The tanks seem to have a leak about a 1/3 of the way from the bottom. The removal of the tanks is a job that has been started. It required removing the teak and holly sole to gain access. The tanks are glassed in to the bilge.

I would think that replacement tanks would require baffles but I'm not an expert (obviously). After the comments made on this forum and reading other web sites, it seems that fiberglass may not be the best idea.

Thanks for the help. The size and complexity of this job raises the stakes and the right decision on the replacement material is important.

[minaret]

I like Interlux Interline 850 for sealing potable water tanks. The same products are used to seal tanks made with other construction methods, they work just as well or better in a glass tank. Much more inert and much less chemical leakage than any metal tank. There are cheaper options than Interlux too.


Interlux Interline Epoxy Tank Coating


Tank Clad HS Epoxy - Protective & Marine

[mikereed100]

Here's a some stuff that can be had in small quantities.

http://www.epoxyproducts.com/datansp120.pdf
NSP 120 epoxy

It's a little worrisome that most potable water tank epoxies come with a caveat that the tank size must be over 1000 gal. Are they telling us the solution to pollution is dilution?
On the other hand, it's probably less toxic than the plastic lining in flexible water tanks.

[thinwater]

Why not repair the SS tank? Did the tank corrode or is it a weld failure? General thinning can't be common.

SS chemical equipment often last 50 years+, through the most awful exposures. If it is a small failure, due to rubbing, a bad weld, or a local disimilar metal problem, it may besimple to repair good-as-new. SS welding is not terribly expensive; most any shop will do it. Don't throw the baby out with the bath.

I've also built FRp tanks. Just get the lining right.

[DeepFrz]

The key to SS tank longevity is proper mounting. They must be mounted so that water cannot collect next to the tank in an oxygen deprived way, such as seeping into the fiberglass that is holding the tank in position. However, 30 or so years in the bilge, with improper installation, doesn't seem like a short lifespan to me. Do you think you will be replacing them again in 30 or so yrs?

[wgh52]

I decided to go back in with new stainless tanks. After considering all the options, I decided that the old stainless had lasted 30 years and therefore I will not need to deal with them in my lifetime. Thanks for all the valuable input.

Bill

[Cheechako]

probably a wise decision!